// if the customer is not logged on, redirect them to the login page
if (!tep_session_is_registered('customer_id')) {
$navigation->set_snapshot();
tep_redirect(tep_href_link(FILENAME_LOGIN, '', 'SSL'));
}

// if there is nothing in the customers cart, redirect them to the shopping cart page
if ($cart->count_contents() < 1) {
tep_redirect(tep_href_link(FILENAME_SHOPPING_CART));
}

// if no shipping method has been selected, redirect the customer to the shipping method selection page
if (!tep_session_is_registered('shipping')) {
tep_redirect(tep_href_link(FILENAME_CHECKOUT_SHIPPING, '', 'SSL'));
}

The installation of this seems to have gone fine the Admin section all looks perfect but for some reason the Discount Codes are not showing up on checkout_payment.php. The original code is present and not altered or uncommented in checkout_payment.php, the HR shows but no Discount Code!